This invention relates to oil and gas wells, particularly surface wells. In particular, the invention relates to a casing string provided in land and offshore petroleum production installations for suspension of casing and for providing a barrier and a fluid conduit between the casing strings.
Slip type casing hangers have been taught in numerous patents of which U.S. Pat. Nos. 6,095,242 and 5,342,066 are incorporated by reference. Also of note are related inventions of U.S. Pat. Nos. 6,138,751, 6,035,938 and 6,015,009. None of the known art has taught an assembly, which provides significant load handling. The present invention, with novel isolation plat and spacer configuration provides an increase of 34-40% in the ability to sustain and transfer load.
A primary objective of the invention is to increase the load capability of the casing hanger by 30 to 40%.
A secondary objective of the invention is to provide a casing hanger assembly, which is adjustable in the field for ease of maintenance without requiring the pulling of the entire assembly, particularly to adjust between the minimum and maximum tolerances of the casing.
Another object of the invention is to provide a means to easily replace packing by utilizing a mechanism that can be readily energized with locking screws, without pulling the entire assembly.
The invention relates to a slip type casing hanger assembly, having a hanger body with an annulus, a casing head disposed around casing for supporting and transferring weight of the casing string to the casing head comprising: (a) an adjustable isolation plate for sealing the annulus, further comprising a lower plate landing on a load shoulder, an upper plate adjoining the annulus, and a spacer separating the lower plate from the upper plates; (b) a plurality of fasteners for securing the spacer to the upper plate and the lower plate; (c) at least two slip segments, each comprising a plurality of teeth for engaging and suspend the casing string, with each slip segment having a top step and bottom step for engaging the hanger body; (d) at least one alignment ring for aligning the slip segments, and (e) locking means for securing the isolation plate against the load shoulder.